What important change in the atmosphere occurred during the Proterozoic Eon?

Question

Question 1 options:

A)

Helium escaped into space and hydrogen was bound into water molecules.

B)

Methane levels decreased and oxygen levels increased, promoting aerobic life forms.

C)

Carbon dioxide levels increased, causing glaciation that cooled the planet.

D)

Nitrogen and carbon dioxide levels decreased, fueling bacterial growth.

Answer 1

The important change in the atmosphere that occurred during the Proterozoic Eon is:

B) Methane levels decreased and oxygen levels increased, promoting aerobic life forms.

During this time, significant geological and biological processes led to the rise of oxygen in the atmosphere, particularly during the Great Oxidation Event, which allowed for the development of aerobic (oxygen-using) life forms.